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J Heighway

Publications and source records attributed to J Heighway.

At least 37 records · Page 2Linked to original sources
PubMed1997

Absence of mutations in the ATM gene in breast cancer patients with severe responses to radiotherapy.

The effectiveness of cancer radiotherapy is compromised by the small proportion (approximately 5%) of patients who sustain severe normal tissue damage after standard radiotherapy treatments. Predictive tests are required to identify these highly radiosensitive cases. Patients with the rare, recessively inherited, cancer-prone syndrome ataxia-telangiectasia (A-T) sustain extremely severe normal tissue necrosis after radiotherapy and their cultured cells are also highly radiosensitive. Clinically normal carriers (heterozygotes) of the A-T gene have an increased risk of breast cancer, account for approximately 4% of all breast cancer cases and show a modest increase in cellular radiosensitivity in vitro. It has been suggested that a substantial proportion of highly radiosensitive (HR) breast cancer patients may be A-T heterozygotes, and that screening for mutations in the A-T gene could be used as a predictive test. We have tested this hypothesis in a group of cancer patients who showed adverse reactions to radiotherapy. Sixteen HR breast cancer patients showing mainly acute reactions (and seven HR patients with other cancers) were tested for ATM mutations using the restriction endonuclease fingerprinting assay. No mutations typical of those found in obligate A-T heterozygotes were detected. If the estimate that 4% of breast cancer cases are A-T gene carriers is correct, then ATM mutations do not confer clinical radiosensitivity. These early results suggest that screening for ATM mutations in cancer patients may not be of value in predicting adverse reactions.

Ataxia Telangiectasia Mutated Proteins↗
PubMed1997

Physical localisation of the breakpoints of a constitutional translocation t(5;6)(q21;q21) in a child with bilateral Wilms' tumour.

A 6 month old boy presented with bilateral Wilms' tumour. Cytogenetic analysis of the lymphocytes from the patient showed a de novo balanced translocation t(5;6)(q21;q21), which was also present in the tumour material as the sole cytogenetic abnormality. To facilitate the identification of the translocation breakpoints, we have established a lymphoblastoid cell line (MA214L) from the patient which maintains the translocation in culture. We have used Genethon microsatellite markers as sequence tagged sites (STSs) to isolate yeast artificial chromosome (YAC) clones to 5q and 6q from human genomic libraries. Using fluorescence in situ hybridisation (FISH) on metaphase preparations of MA214L, we have physically defined the translocation breakpoints between YAC clones on each chromosome arm. The genetic distance separating the flanking YACs on 6q21 is 3 cM, while that on 5q21 is 4 cM. To date this is the first report of these chromosomal regions being implicated in Wilms' tumourigenesis.

Chromosome Fragility↗
PubMed1996

Coamplification in tumors of KRAS2, type 2 inositol 1,4,5 triphosphate receptor gene, and a novel human gene, KRAG.

Analysis of a region of DNA, coamplified in tumors with KRAS2, resulted in the identification of the human homologue of the mouse KRAG gene. The gene was widely expressed in a range of cell lines, tumors, and normal tissue and demonstrated a high degree of alternate splicing. A human KRAG cDNA sequence, with a structure similar to that encoded by the amplified gene in mouse Y1 adrenal carcinoma cells, was isolated by RT-PCR. The predicted amino acid similarity between the two sequences was 91%, and hydrophobicity plots suggested a structure closely resembling that of transmembrane 4 superfamily members. Identification of a PCR-based restriction fragment length polymorphism confirmed biallelic expression of KRAG but suggested allele-specific splicing differences in tumors. Northern analysis of mRNA derived from a range of tissues suggested high level expression in muscle and confirmed alternate splicing. To facilitate the analysis of exon junctions, a YAC clone encoding the genomic sequence was identified. This allowed the localization of KRAG to human chromosome 12p11.2. Isolation of one end of this nonchimeric clone demonstrated a perfect match with a 247-bp sequence within the 3' untranslated region of the type 2 1,4, 5-inositol triphosphate receptor gene. Multiplex PCR confirmed the inclusion of both genes in the KRAS2 amplicon in human malignancy, suggesting that either may contribute to the malignant phenotype.

Alleles↗
PubMed1996

No defect in G1/S cell cycle arrest in irradiated Li-Fraumeni lymphoblastoid cell lines.

The radiation response of Epstein-Barr virus (EBV)-immortalised lymphoblastoid cell lines derive from Li-Fraumeni syndrome (LFS) and LFS-like individuals was investigated. Cells from all LFS and LFS-like cases showed an accumulation of p53 protein following 137Cs gamma-irradiation, which was associated with cell cycle arrest at the G1/S border. This response was indistinguishable from that seen in cells derived from normal individuals, and occurred in cases with missense mutations in the TP53 gene at codons 175, 180, 220 and 248 and also in two LFS-like individuals with no TP53 mutation. Previous studies using lymphocytes and fibroblasts from LFS individuals have demonstrated abnormal radiation responses in these cells. This suggest cell type specificity in the contribution of a mutant p53 protein to phenotype.

Burkitt Lymphoma↗
PubMed1996

High levels of loss at the 17p telomere suggest the close proximity of a tumour suppressor.

High levels of loss of distal markers on 17p13.3 in breast cancer suggested the presence within the region of at least one tumour-suppressor gene. Here we describe the derivation of two biallelic polymorphisms from the 17p telomeric yeast artificial chromosome (YAC) TYAC98. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and multiplex PCR analysis demonstrated that the high level of allelic imbalance observed in breast tumours represented loss of constitutional heterozygosity (LOH) and that this LOH extended to the telomere. Lung carcinoma (but not Wilms' tumour)-derived DNA again revealed a high level of loss of subtelomeric 17p sequences. Telomeric microsatellite polymorphisms from other chromosome arms did not show such elevated loss in either tumour type. This suggested that the 17p loss observed did not reflect a general telomeric instability and provided further evidence for the presence of a breast cancer tumour-suppressor gene in the distal region of 17p13.3.

Breast Neoplasms↗
PubMed1996

Prognostic significance of CCND1 (cyclin D1) overexpression in primary resected non-small-cell lung cancer.

Amplification of the CCDN1 gene encoding cyclin D1 was examined by Southern blotting and multiplex polymerase chain reaction (PCR) and occurred in 8 of 53 patients (15%) with primary resected non-small-cell lung cancer (NSCLC). These tumours and 17 additional tumours with a normal gene copy number showed overexpression of cyclin D1 (25/53, 47%), as assessed by immunostaining using a monoclonal antibody. In 22/25 cases, cyclin D1 was localised in the cytoplasm, but some (7/25) had simultaneous nuclear staining. This result is in marked contrast to that reported in breast, hepatocellular and colorectal carcinoma studies where immunostaining was invariably nuclear. Examination of a restriction fragment length polymorphic (RFLP) site within the 3'untranslated region of the cDNA following reverse transcriptase (RT)-PCR (29/53 informative cases) showed a strong association between cytoplasmic staining and imbalance in allele-specific message levels. Cyclin D1 overexpression was associated with a poorly differentiated histology (P = 0.04), less lymphocytic infiltration of the tumour (P = 0.02) and a reduction in local relapse rate (P = 0.01). The relative risk of local relapse was 9.1 in tumours without cyclin D1 overexpression (P = 0.01, Cox regression analysis). We conclude that genetic alteration of cyclin D1 is a key abnormality in lung carcinogenesis and may have diagnostic and prognostic importance in the treatment of resectable NSCLC.

Aged↗
PubMed1996

Fibroblasts from Li-Fraumeni patients are resistant to low dose-rate irradiation.

A group of adult skin fibroblast cultures from four individuals representing Li-Fraumeni families with different mutations in the p53 gene were found to be resistant to low dose-rate (0.011 Gy per min) 60Co radiation when compared with a control group of four cultures from normal individuals. The Li-Fraumeni fibroblasts, which could not be distinguished from controls after high dose rate (1.07 Gy per min) irradiation, were shown to be heterozygous (+/mut) at the p53 locus at the time of irradiation.

Adolescent↗
PubMed1995

Alternate splicing produces a novel cyclin D1 transcript.

Using Northern blotting and PCR analysis of cDNA derived from a range of cell lines and tissues, alternate splicing of the cyclin D1 gene (CCND1) mRNA has been demonstrated. The variant transcript shows no splicing at the downstream exon 4 boundary, encoding a protein with an altered carboxy-terminal domain. Investigation of mRNA extracted from mononuclear cells, lung tumour and normal tissue suggests that both transcripts are invariably expressed. However, splicing to produce the two forms of mRNA is modulated, in the heterozygote, by a frequent A/G polymorphism located within the splice donor region of exon 4. Preliminary analysis of patients with resectable non-small cell lung cancer suggests that genotype is associated with shortened event free survival and greater risk of local relapse.

Aged↗
PubMed1995

Genome-wide loss of maternal alleles in a nephrogenic rest and Wilms' tumour from a BWS patient.

A patient with Beckwith-Wiedemann syndrome (BWS) presented with Wilms' tumour. Examination of the nephrectomy specimen showed, in addition to the tumour, the presence of nephrogenic rests. Nephrogenic rests are thought to be precursor lesions from which a Wilms' tumour may develop. A molecular analysis examining the loss of constitutional heterozygosity (LOCH), initially for chromosome 11, was performed on peripheral blood, the normal kidney, nephrogenic rest and tumour material. The study was extended to include markers from all 23 chromosomes. At each informative, locus, LOCH of the maternal allele was shown in the nephrogenic rest and tumour material. In addition, the normal kidney displayed allele imbalance. It would appear from these results that either extensive LOCH across the genome was an early genetic event in the development of malignancy in this patient or that the tumour and rest developed from cells containing no maternal chromosomes. The apparent LOCH seen in the normal kidney sample implies that full reduction to homozygosity is consistent with a histologically normal appearance. Putative mechanisms to explain this phenomenon are discussed.

Alleles↗
PubMed1995

Mapping of gene loci in the Q13-Q15 region of chromosome 12.

The gene loci CDK4, GLI, CHOP and MDM2 have been mapped to the q13-q15 region of chromosome 12. Using fluorescence in situ hybridization onto simultaneously DAPI-banded metaphase chromosomes and interphase nuclei, we have more precisely mapped and ordered these loci, together with a number of Genethon microsatellite markers. GLI and CHOP localize to 12q13.3-14.1, CDK4 to 12q14 and MDM2 to 12q14.3-q15, and the gene order is cen-GLI/CHOP-CDK4-MDM2. The Genethon microsatellites D12S80 and D12S83 flank MDM2.

CCAAT-Enhancer-Binding Proteins↗
PubMed1995

Detailed mapping and loss of heterozygosity analysis suggests a suppressor locus involved in sporadic breast cancer within a distal region of chromosome band 17p13.3.

The chromosome region 17p13.3 is thought to encode a tumour suppressor gene involved in sporadic breast cancer and other malignancies. Physical ordering of markers has been carried out by a series of multicolour fluorescent in situ hybridisation (FISH) experiments, using isolated yeast artificial chromosomes (YACs) and cosmids. Eight polymorphic markers ordered within this new physical map and one external marker were used to investigate the pattern of loss of heterozygosity in a panel of 40 sporadic breast tumour patients. The data revealed a region of high loss (60%) within distal 17p13.3, defined by markers D17S926, D17S695 and D17S849 which mapped close together. A contig of YACs was constructed physically linking these three markers.

Base Sequence↗
PubMed1994

A transcribed polymorphism and sub-localisation of MDM2.

An NlaIV polymorphism in the 5' untranslated region of the MDM2 gene is described. MDM2 was sublocalised by fluorescence in situ hybridisation with a yeast artificial chromosome probe to 12q14.3-12q15. We demonstrate the use of the polymorphism to assess allelic imbalance in breast tumours.

Alleles↗
PubMed1994

Linkage studies in a Li-Fraumeni family with increased expression of p53 protein but no germline mutation in p53.

We report a family with the Li-Fraumeni syndrome (LFS) in whom we have been unable to detect a mutation in the coding sequence of the p53 gene. Analysis of linkage to three polymorphic markers within p53 enabled direct involvement of p53 to be excluded. This is the first example of a LFS family in whom exclusion of p53 has been possible. Four affected members of the family with sarcoma or premenopausal breast cancer showed increased expression of p53 protein in their normal tissues as detected by immunohistochemistry. It therefore appears that the LFS phenotype has been conferred by an aberrant gene, showing a dominant pattern of inheritance, which may be acting to compromise normal p53 function rather than by a mutation in p53 itself. In order to try to determine the chromosomal location of this putative gene, we have carried out studies of linkage to candidate loci. By these means we have excluded involvement of Rb1 and BRCA1 on chromosomes 13q and 17q respectively. The MDM2 oncogene on chromosome 12q was considered to be the prime candidate as MDM2 is amplified in sarcomas and the MDM2 product binds to p53. Furthermore, p53 mutation and amplification of MDM2 have been shown to be mutually exclusive events in tumour development. Linkage analysis to two polymorphic markers within MDM2 yielded a three-point LOD score of -5.4 at a recombination fraction theta equal to zero. Therefore MDM2 could be excluded. It is possible that the gene which is responsible for cancer susceptibility in this family, possibly via interaction with p53, will be important in the histogenesis of breast cancer in general. We are now carrying out further studies to locate and identify this gene.

Base Sequence↗
PubMed1994

Rare variant (Glu to Lys) in the leucine zipper region of CHOP (GADD153).

CHOP (GADD153) has been shown to be a dominant negative inhibitor of specific transcription factors. Direct sequencing of the gene, amplified from the DNA of a Li-Fraumeni family index case (liposarcoma, breast cancer) revealed a constitutional variant within the coding region. This alteration, though not responsible for the Li-Fraumeni phenotype, resulted in a glutamic acid to lysine switch within the leucine zipper domain, at a residue conserved between CHOP and its potential target molecules and between the human and hamster sequences. The variant created a Taq I restriction fragment length polymorphism (RFLP) facilitating screening. Analysis of 159 breast tumour DNA samples detected two encoding variant alleles (tumour and constitutional DNA).

Adult↗
PubMed1993

A polymerase chain reaction-based method for the detection of trisomy 12 in B chronic lymphocytic leukaemia.

We report a polymerase chain reaction (PCR)-based method for detection of clonal trisomy 12 cell populations in B cell chronic lymphocytic leukaemia which is particularly applicable to retrospective analysis or archival material. The method utilizes three restriction enzyme site polymorphisms linked to the KRAS2 locus on chromosome 12 to monitor allele imbalance resulting from duplication of this chromosome. 21/24 unselected chronic lymphocytic leukaemia cases (88%) were informative for at least one polymorphism and of these, eight (33% of total cases) displayed allelic imbalance consistent with trisomy 12.

Base Sequence↗